1. Field of Invention
The present invention relates to electronic gear, and more specifically, to solid state modular control units having a heat dissipating chassis or housing.
2. Prior Art
It is a known fact that electronic circuits operating at a relatively high power level generate substantial amounts of heat. The heat is normally removed by forcing air to circulate through the interior of the chassis or housing of the apparatus. This technique is satisfactory in most cases. However in applications where the air in the operating environment contains dust, soot and other pollutants, the heat exchange surfaces inside the chassis tend to accumulate a layer of foreign substances which eventually become an effective insulator hampering the cooling of these surfaces by the air. When this condition occurs, electronic components in the circuit overheat and eventually fail.
The technique of mounting "heat sinks" on the heat producing components and exposing the heat sink surfaces to the air outside the chassis has also been employed successfully. However this has not been practical where the heat producing components are located on a module which gets power from a main chassis and is designed to be easily unplugged and replaced.